Agricultural harvesters typically include a self-propelled vehicle including crop threshing, separating, or cleaning equipment, and a header attached to the front of the vehicle that the vehicle carries through the field. The header cuts the crop and conveys it to the center of the header using belt or auger conveyors. A second, central cylindrical conveyor is located in the center of the header, typically configured as a cylinder with outwardly extending fingers. The fingers engage the cut crop matter and pull it rearward under the cylinder of the cylindrical conveyor and into the self-propelled vehicle.
In a cylindrical conveyor design, the outwardly extending fingers are not fixed to the outer surface of the cylinder, but are supported at one end on a timing crank that is disposed inside the cylinder, which is hollow. The fingers extend through apertures formed in the cylindrical wall of the cylinder. As the cylinder is driven in rotation about its central longitudinal axis, it drives the fingers in a circular path about the longitudinal axis of an offset shaft that is supported by the timing crank.
The timing crank and the offset shaft that it supports are offset from the longitudinal axis of the central conveyor cylinder. This offset makes the fingers alternately extend from and retract into the cylinder as the cylinder rotates and drives the fingers in their circular path.
The timing crank is typically offset toward the front of the cylinder (and hence the front of the harvester) to permit the fingers to extend farther outward and forward when first engaging the cut crop material. As the cylinder rotates, the fingers pull the cut crop material downward and underneath the cylinder, across a pan or floor, and toward the self-propelled vehicle. Once the cut crop material has been drawn underneath the cylinder, the offset relationship causes the fingers to withdraw into the cylinder, thereby releasing the cut crop material and permitting it to leave the header and be drawn into the self-propelled vehicle for threshing, separating, and cleaning.
The central cylindrical conveyor is preferably configured to be disassembled for cleaning and repair. Part of this disassembly includes removal of the timing crank.
A particular problem for cylindrical conveyors in agricultural environments is the possibility of unwanted rocks or other field trash being drawn into the conveyor. When the fingers engage this material, it places a very high stress on the fingers, which is transferred to the timing cranks which support them.
What is needed, therefore, is a timing crank, conveyor and header that are better able to resist these large stresses. It is an object of this invention to provide such an timing crank, conveyor and header.